But really the biggest selling point of the next iPhone is its upgraded screen size, according to Morgan Stanley analyst Kay Huberty, who is noted for coining the popular term 'iPhone killer features'.

And what could prove as the main killer feature packed with the iPhone 6 is its jumbo profile, thanks to the 5.5-inch screen upsize that Ming-chi Kuo of KGI Securities said Apple will deploy later on in the year. In fact, Kuo's crystal balls are pointing to two builds - the 4.7-inch iPhone and the 5.5-inch model that will serve as the first iOS phablet.

The latter is what will bring the giant cash windfall for Apple in closing out 2014, Huberty said in her latest note to investors.

Around five out of 10 existing smartphone owners have expressed desire to buy the iPhone 6 phablet once it becomes available, the Morgan Stanley analyst was reported by Apple Insider as saying.

This surge of shoppers will redound for Apple a blockbuster Q4 2014 with the tech titan likely to clear some 66 million units or more if the 5.5-inch iPhone is part of the iOS device menu. But if Apple will leave out the 5-inch+ iPhone, its projected sales could retreat by as much as 15 million units, Huberty predicted.

The Morgan Stanley report also suggested that apart from having a supersized screen, consumers also consider other key factors before deciding on a buy.

"The top criteria across all brands are longer battery life, software/operating system, and lower price, though current Apple users think price is of lesser importance," Huberty's report was quoted by BGR as saying in a separate article.

Another would-be attraction of the iPhone 6 phablet is its reported camera upgrades despite indications that main shooter for the upcoming iOS device will remain 8MP.

According to CNET, while Apple will continue to shy away from the megapixel war being waged by the likes of Samsung, Sony, LG and Nokia the company will provide two key camera bump ups with the iPhone 6, which is true for both the 4.7-inch and 5.5-inch models.

The iPhone 6 camera pixel size will jump from 1.5um to 1.75um that ensures the shooter will capture more light and therefore produce higher quality images. Also, electronic image stabilization (EMS) technology will be stuffed with the rear cam for sharper picture colours.

ESM-China analyst Sun Chang Xu hinted too, CNET added, that Apple originally planned to use optical image stabilisation (OIS) with the iPhone 6 but altered course at the last minute as OIS will not fit in with the slim and light profile of the device.

Somehow, this confirms that the next iPhone will sport a 6mm-thin body.

Release date of the iPhone 6 is thought to happen in September 2014, which is for the 4.7-inch version, while the bigger 5.5-inch build will not be unboxed until December this same year due to display production challenges.